Metallic coating film glitters by an incident light from outside reflected at a metallic pigment contained in the coating film and has a specific beautiful appearance rich in variation coupled with various color tones of the coating film. Therefore, the coating film is applied particularly to metal articles of automobiles, motorcycles, and the like.
As a method for forming the metallic coating film, Japanese Patent Publication No. 38267/1990 describes a metallic coating method wherein, on a metallic base coating film containing a relatively deep-colored pigment, a colored clear coating film containing a high-chroma pigment having a similar color to that of the relatively deep-colored pigment is formed. Moreover, WO97/47396 (U.S. Pat. No. 6,165,621) describes a method for forming a metallic coating film wherein a metallic base coating, a transparent second base coating, and a clear coating are successively applied.
However, in the method described in Japanese Patent No. 2-38267, since the relatively dark-colored pigment in the metallic base coating film lowers a metallic feeling, there arises a problem that it is difficult to obtain a deepness feeling and a high-chroma feeling of the metallic coating film. Moreover, in the method described in WO97/47396, since a slight variation of the thickness of the transparent second base coating film changes a coating color to a large extent, there arise problems that it is difficult to control a coating line and also the color of the edge part which is apt to have a larger film thickness as compared to an ordinary part becomes dark, i.e., so-called frame phenomenon occurs.
Thus, the present applicant has proposed a method for forming a metallic coating film, which is capable of obtaining a metallic coating film excellent in a deepness feeling and a high-chroma feeling and which also exhibits a small variation of the coating color by film thickness variation and allows an easy control of the coating line without occurrence of the frame phenomenon, by forming a bilayer colored clear coating film having a specific light transmittance on a metallic base coating film and preferably making the coating color of the metallic base coating film a specific one (for example, cf. Japanese Patent Laid-Open No. 2002-86057). However, a coating color having denser particle feeling and metallic feeling has been desired and the method described in Japanese Patent Laid-Open No. 86057/2002 is insufficient.